The invention relates generally to fiber optic sensing devices, and more particularly, to a fiber optic sensing system and method for detecting multiple parameters from a power generation system or a component, for example, a turbomachine such as a steam turbine, or the like.
Turbomachines such as a steam turbine plant may include several steam or condensate pipes leading to and from a steam turbine and accessories of the plant. The steam or condensate pipes may also be provided with several valves. Steam condensation may occur at various points in the pipes, valves, and steam turbine. This condensation can slow starting or loading of the steam turbine. If the condensation is not detected, it can damage the steam turbine during start-up, loading or operating conditions of the turbine. Monitoring temperature at the various points of the steam turbine plant more continuously (rather than discretely) can help to identify the water or moisture traps and improve steam turbine and plant operability. It is difficult, however, to monitor temperature at all points where condensation can occur or water can collect due to the configuration of the various steam or condensate pipes, valves, and steam entry and exit points in the plant.
Additionally, the steam turbine casing has a temperature gradient and expands differently at different portions due to transient operation and its complex geometry. Understanding the distributed temperature of the casing during operation would greatly help to understand the expansion and clearances within the turbine. Knowledge regarding the operation information such as temperature, thermal expansion, moisture content related to the steam turbine system improves steam turbine and plant operability.
Conventionally, the internal temperatures of a steam turbine are measured by a small number of individual thermocouples or resistance temperature detectors positioned within the turbine casing, valve and piping locations. One limitation of the thermocouples is that thermocouples are single point measurements and can be easily misplaced in a region close to an intended target area resulting in a vastly different temperature reading due to the complex geometry of the turbine casing and internal heating conditions. It is difficult and expensive to provide large number of thermocouples in a distributed manner around the turbine.
It is desirable to have an economical device and method that can be used to extract one or more parameters such as temperature, thermal expansion, moisture content, or the like of a device such as a steam turbine for improving device operability, and also for providing optimized control of device for power generation.